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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 22 |
| 4 | 207 |
| 5 | 2412 |
| 6 | 31754 |
| 7 | 452640 |
| 8 | 6840774 |
| 9 | 108088232 |
| 10 | 1768560270 |
| 11 | 29764630632 |
| 12 | 512705615350 |
| 13 | 9005206632672 |
| 14 | 160810554015408 |
| 15 | 2912940755956084 |
| 16 | 53424552150523386 |
[1,0,3,22,207,2412,31754,452640,6840774,108088232, 1768560270,29764630632,512705615350,9005206632672, 160810554015408,2912940755956084, 53424552150523386] |